U.S. patent number 4,024,159 [Application Number 05/495,510] was granted by the patent office on 1977-05-17 for process for the production of liquid acetals.
This patent grant is currently assigned to E. I. Du Pont de Nemours and Company. Invention is credited to Marvin L. Peterson.
United States Patent |
4,024,159 |
Peterson |
May 17, 1977 |
**Please see images for:
( Certificate of Correction ) ** |
Process for the production of liquid acetals
Abstract
Alcohols and/or alpha, beta or alpha, gamma diols having at
least four carbon atoms are reacted with aldehyde or dialdehyde
compounds at a temperature ranging from 0.degree. - 100.degree. C
in the presence of an acid catalyst to produce an organic-aqueous
two-phase liquid product containing the acetal in the organic
phase.
Inventors: |
Peterson; Marvin L. (Woodstown,
NJ) |
Assignee: |
E. I. Du Pont de Nemours and
Company (Wilmington, DE)
|
Family
ID: |
23968921 |
Appl.
No.: |
05/495,510 |
Filed: |
August 7, 1974 |
Current U.S.
Class: |
549/369; 568/603;
568/594 |
Current CPC
Class: |
C07D
317/22 (20130101); C07D 319/06 (20130101) |
Current International
Class: |
C07D
317/00 (20060101); C07D 319/00 (20060101); C07D
319/06 (20060101); C07D 317/22 (20060101); C07D
319/06 () |
Field of
Search: |
;260/340.7 (U.S./ only)/
;260/615A |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Sutto; Anton H.
Claims
What is claimed is:
1. In a process for preparing acetals by reacting diols with
aldehydes the improvement which comprises reacting an alpha, beta
diol; mixtures thereof; an alpha, gamma diol or mixtures thereof
wherein said diol has 4 to 20 carbon atoms at a temperature ranging
from 0.degree.-100.degree. C in the presence of an acid catalyst
with from a stoichiometrically equivalent quantity to a 50% excess
of an aldehyde having 1 to 4 carbon atoms to yield a liquid acetal
having a solubility of less than 10% by weight in water at
25.degree. C.
2. The improvement of claim 1 wherein the acid catalyst is a
strongly acidic water insoluble ion exchange resin.
3. The improvement of claim 1 wherein the temperature ranges from
25.degree. to 50.degree. C.
4. The improvement of claim 1 wherein the alcohol is
2-methyl-1,3-propanediol.
5. The improvement of claim 1 wherein the aldehyde is acrolein.
6. The improvement of claim 1 wherein the acetal is a
1,3-dioxane.
7. The process of claim 1 wherein the aldehyde is selected from
acetaldehyde, acrolein, propionaldehyde, methacrolein and
formaldehyde.
Description
BACKGROUND OF THE INVENTION
Many patents disclose conditions for converting aldehydes to
acetals. For example, U.S. Pat. No. 2,131,998 discloses the
addition of an alcohol to a double bond as well as acetal
formation, i.e., ##STR1## U.S. Pat. No. 2,566,559 discloses the use
of a fixed bed cation exchange resin as a catalyst for the
preparation of acetals and U.S. Pat. No. 2,840,615 discloses the
use of strongly acidic cation exchange resins as catalysts for
acetal formation from methanol and acetaldehyde. U.S. Pat. No.
2,678,950 discloses the use of sulfo acid catalysts with continuous
removal of water from the reaction mixture and U.S. Pat. No.
3,014,924 discloses the use of highly porous silica-alumina
catalysts impregnated with a small quantity of a strong mineral
acid. U.S. Pat. No. 2,987,524 discloses the preparation of cyclic
unsaturated acetals using a sulfo acid catalyst with continuous
removal of water. U.S. Pat. No. 2,729,650 discloses the preparation
of unsaturated cyclic acetals using inorganic salts as
catalysts.
The reactions of alcohols with aldehydes to form acetals are
equilibrium reactions. The degree of conversion to the acetal is
limited by the equilibrium constant for the reaction, unless one of
the products can be removed from the reaction site. ##STR2##
K is the equilibrium constant, and the various C's represent the
molar concentrations of reactants and products. The equilibrium
constant for the reaction of methanol with acetaldehyde allows only
about a 50% conversion to acetal while the reaction of acrolein
with 2-methyl-1,3-propanediol (MPD) yields only 65% of acetal under
equilibrium conditions.
Several techniques have been used in an attempt to obtain
conversions of reactants to acetals at concentrations higher than
the equilibrium concentration. The most common technique used is
the completion of the reaction by azeotropic distillation of water
with a water-insoluble organic solvent such as benzene or toluene
as disclosed in U.S. Pat. No. 2,987,524. Such a process suffers
from several basic deficiencies. The overall efficiency is low
because low yields of acetal are obtained per volume of reactor
space, a high energy consumption is needed for the azeotropic
distillation, acetal product must be separated by distillation from
the solvent, the cost of solvent adds to the process cost and at
the temperatures and times required for azeotropic distillation,
unsaturated aldehydes, such as acrolein, react to form side
products by polymerization and addition of water and alcohols to
the carbon-carbon double bond.
Large excesses of one reactant, usually the alcohol, have been used
to drive the equilibrium toward higher conversions with more
complete utilization of the aldehyde. U.S. Pat. No. 2,566,559
teaches the preferred use of 4 to 5 moles of alcohol per mole of
aldehyde. The acetal product must be separated from the large
excess of alcohol, and the alcohol recovered and recycled to the
process. High molar ratios of aldehyde/alcohol may be used, but
side polymerization reactions and additions to the double bond may
consume some of the unsaturated aldehydes.
Water has also been removed from the reaction by dessicants, such
as calcium chloride as disclosed in German Patent 434,989. These
systems are difficult to handle and costly to operate, because the
dessicant must be recovered, dried and returned to the process.
SUMMARY OF THE INVENTION
It has now been found that liquid acetals having a solubility of
less than 10% by weight in water at 25.degree. C can be prepared at
higher than equilibrium concentration yields by reacting an alcohol
and/or diol having at least four carbon atoms and a maximum of
three carbon atoms separating the diol hydroxyl groups, (alpha,
beta or alpha, gamma diols) at a temperature ranging from
0.degree.-100.degree. C in the presence of an acid catalyst, with
at least a stoichiometrically equivalent quantity of an aldehyde
and/or dialdehyde. A two-phase aqueous-organic liquid product is
obtained in which the acetal is contained in the organic phase. The
aldehyde and/or dialdehyde is generally a saturated or unsaturated
alkyl (C.sub.1 -C.sub.20), alkaryl (C.sub.7 -C.sub.20) or aralkyl
(C.sub.7 -C.sub.20) compound which may contain chlorine, bromine,
alkyl (C.sub.1 -C.sub.10), aryl (phenyl, naphthyl), carbalkoxy
(C.sub.1 -C.sub.10 in alkoxy), alkoxy (C.sub.1 -C.sub.10) and the
like substituents which will not solubilize the organic-acetal
layers or interfere with the alcohol-aldehyde reaction. The alkyl
group may be cycloalkyl and the aryl groups in the alkaryl and
aralkyl groups are generally phenyl or naphthyl.
Because of the formation of two distinct layers, the reaction
product in the organic phase is effectively removed from the
reactants in the aqueous phase before equilibrium is reached. Thus,
higher conversions to acetal and higher yields are obtained than
had been possible heretofore. The process is particularly effective
for preparing acetals having six-membered rings (1,3-dioxanes) from
1,3-diols and aldehydes since the stability of the six-membered
ring promotes a higher conversion to acetal before equilibrium is
reached. The surprisingly low solubility of water in such acetals
and vice versa favors layer separation.
The present process is also advantageous since it does not require
large excesses of reactants that must be recovered, solvents that
must be recovered, dessicating agents or azeotropic distillation of
water with high energy consumption.
DETAILED DESCRIPTION OF THE INVENTION
As used herein, the term alcohol is intended to include alpha, beta
and alpha, gamma diols and the term aldehyde is intended to include
dialdehydes and mixtures of each.
Any alcohol having at least four carbon atoms may be used in the
practice of this invention. Compounds containing three or more
hydroxyl groups cannot be used because the additional alcohol
functional groups tend to solubilize the system so that the
distinct organic-aqueous phases to not form. Conversions to acetal
increase with increasing chain length of the alcohol. Preferably,
however, the alcohol should contain a maximum of 20 carbon atoms in
either a straight or branched chain since a large number of carbon
atoms might result in a solid acetal product. Some specific
alcohols which may be used include, for example,
2-methyl-1,3-propanediol, 1,3-butanediol, 2,4-pentanediol,
2,2-dimethyl-1,3-propanediol, 2-ethyl-1,3-propanediol,
2-methyl-2,4-pentanediol, 1,3-pentanediol, 2,4-hexanediol,
1,3-hexanediol, 2,2-diethyl-1,3-propanediol, 1,3-heptanediol, 2,4-
or 3,5-heptanediol, 2,3-butanediol, 2,3-dimethyl-2,3-butanediol,
2,3-diethyl-2,3-butanediol, butyl, amyl, hexyl, heptyl, octyl,
decyl, lauryl, myristyl, stearyl, crotyl, benzyl, cinnamyl,
isobutyl, isoamyl, 4-methyl-1-pentanol, 3-methyl-1-pentanol,
2,3-dimethyl-1-pentanol, 2-ethyl-1-hexanol, 2-phenyl-1-ethanol and
the like alcohols and mixtures thereof. Any alcohols containing
hetero atoms such as oxygen, sulfur, carbonate and the like atoms
or groups in the hydrocarbon structure may also be used as well as
those containing substituents such as alkoxy (C.sub.1 -C.sub.4),
aryloxy (benzoxy, naphthoxy), halogen (chlorine, fluorine, bromine,
iodine), --NO.sub.2, --SH and the like. Some examples of such
alcohols include 4-chloro-1-butanol, 4-bromo-1-butanol, 3,4, or
5-chloro-1-pentanol, 4-iodo-1-butanol, 2-ethoxy-1-ethanol,
3-methoxy-1-propanol, 4-methoxy-1-butanol, 2-butoxy-1-ethanol,
3-butylthio-1-propanol, 4-methylthio-1-butanol,
3-acetoxy-1-propanol, 4-acetoxy-1-butanol, 3-nitro-1-butanol,
furfuryl alcohol, 3-benzoxy-1-propanol, 2-benzoxy-1-ethanol,
2-naphthoxy-1-ethanol, 4-nitro-1-butanol,
2-(p-nitrophenoxy)-1-ethanol, p-chlorobenzyl alcohol and the like
and mixtures thereof.
The process of the invention may be used to prepare acetals of any
cyclic or acyclic, saturated or unsaturated aliphatic or aromatic
aldehyde that reacts with an alcohol having four or more carbon
atoms to yield an acetal which has a solubility of less than 10% by
weight in water at 25.degree. C. Suitable aldehydes range from
saturated aldehydes prepared from formaldehyde to the long carbon
chain aldehydes and dialdehydes. High molecular weight and/or solid
aldehydes may be used if they are soluble in the alcohol or any
medium used for reaction with the alcohol. The process of the
invention is particularly suited to the preparation of acetals from
unsaturated aldehydes, such as acrolein, because the reaction
conditions are mild so that unwanted side reactions do not occur.
The aldehyde or dialdehyde may also contain the same substituents
described above for the alcohols or diols. Some specific examples
of suitable aldehydes and dialdehydes include formaldehyde,
acetaldehyde, propionaldehyde, butyraldehyde, valeraldehyde,
isobutyraldehyde, isovaleraldehyde, caproaldehyde, heptaldehyde,
octaldehyde, capric aldehyde, stearaldehyde, acrolein,
crotonaldehyde, benzaldehyde, furfural, glyoxal,
phenylpropargylaldehyde, 3-penten-1-al, 2-penten-1-al,
3-methyl-2-penten-1-al, cinnamaldehyde, p-chlorbenzaldehyde,
p-bromobenzaldehyde, m-nitrobenzaldehyde, p-fluorobenzaldehyde,
p-methoxybenzaldehyde, o-methoxybenzaldehyde, naphthaldehyde,
g-acetoxybutyraldehyde, diethyl a-formylsuccinate,
formylcyclopentane, trimethylacetaldehyde, ethyl glyoxylate,
chloroacetaldehyde, 3-bromopropionaldehyde, terephthalaldehyde,
ethyl p-formylbenzoate, and the like and mixtures thereof.
The alcohol should be reacted with the aldehyde in stoichiometric
proportions for best results although as much as a 50% excess of
the aldehyde may be employed. Higher concentrations of aldehyde or
greater than stoichiometric equivalent amounts of alcohol tend to
solubilize the system and prevent phase separation. In addition,
great excesses of unsaturated aldehyde or dialdehyde result in
by-product formation via reaction across the double bond.
Preferably, 1 equivalent of alcohol or diol to a range of 1-1.5
equivalents of aldehyde or dialdehyde is used.
Generally, the reactants are miscible liquids or else one is
soluble in the other so that no solvent need be employed in
carrying out the reaction. Therefore, the alcohol and aldehyde each
may be introduced to the reaction per se or, if desired, they may
be introduced in aqueous solution. However, since too high a
concentration of water may cause solubility problems, the medium in
which the reaction is carried out should contain only 0 to 10% by
weight of water based on the weight of the alcohol or diol and
aldehyde or dialdehyde. However, any amount of water which can be
handled easily in the reactor and during separation of the two
phases may be employed.
The reactions of the process of this invention are acid-catalyzed
and conventional acid catalysts may be used. Soluble mineral acids,
such as hydrochloric acid, sulfuric acid and phosphoric acid
catalyze the reaction strongly. Organic sulfonic acids, such as
p-toluenesulfonic acid, and are also excellent catalysts. Reaction
mixtures employing these soluble catalysts are homogeneous until
separation of phases begins. The disadvantage of using soluble
catalysts is that they must be neutralized before further
processing of the reaction product to avoid product hydrolysis
during work up. Therefore, in a preferred embodiment of this
invention, insoluble, heterogeneous catalysts of the strongly
acidic cationic exchange resin type are used. These catalysts are
advantageous because they are easily separated from reaction
product and a neutral reaction product is produced. They have a
long life and may be used repeatedly. The resins may be used either
in a stirred slurry system or as a fixed bed catalyst through which
the reactants are passed.
Any strongly acidic water insoluble ion exchange resin can be used
in the practice of this invention. Typical such resins are those
containing sulfonic acid groups such as the resins disclosed in
U.S. Pat. 2,366,007 issued Dec. 26, 1944 to G. F. D'Alelio which
include sulfonated styrene-divinyl benzene copolymers commercially
available as Dowex, Amberlite and the like resins. Other suitable
cation-exchange resins include, for example, the phenol sulfonic
acid-formaldehyde reaction products.
Any suitable reactor may be used to carry out the reaction
including a simple pot. Generally, however, for continuous
reactions, a reactor with a fixed catalyst bed of an insoluble
strongly acidic ion exchange resin through which the reactants are
passed is preferred.
The temperature of the reactor may vary from 0.degree. to
100.degree. C with a preferred temperature range from 25.degree. to
50.degree. C. The best temperature in each case will be determined
by the reactants used. At temperatures lower than 25.degree. C, the
reaction may be too slow to be commercial. At temperatures above
50.degree. C, unsaturated aldehydes such as acrolein tend to
undergo side reactions.
Any apparatus may be employed which can be used conveniently to
separate the organic from the aqueous phase after the reaction is
completed. Since the process of this invention may be carried out
either batchwise or continuously, phase separation may also be
achieved either batchwise or on a continuous basis. In a batch
process, the reaction layers will be separated by draining the
lower aqueous layer from the acetal layer in a separating funnel or
similar larger scale commercial equipment. In a continuous process,
the reaction products will be fed to a decanter which continuously
separates the layers.
The invention is further illustrated but is not intended to be
limited by the following examples in which all parts and
percentages are by weight unless otherwise specified.
EXAMPLE 1
2-vinyl-5-methyl-1,3-dioxane (VMD)
A mixture of 1 molar equivalent of 2-methyl-1,3-propanediol (MPD)
and 1.1 molar eq. of acrolein was passed through a column (1/4 inch
.times. 6 inches) of 10 ml. of strongly acidic cationic exchange
resin (Dowex MSC-1) at the rate of 0.55 g./min. The bed was cooled
with circulating water at 25.degree. C and the maximum temperature
in the resin bed was 35.degree. C. The reaction product (30.7 g.)
divided into 2 layers -- an acetal layer (26.6 g.) and an aqueous
layer (4.1 g.). The layers were each analyzed by gas-liquid phase
chromatography. The acetal layer contained 79% VMD, 3% MPD, 8%
acrolein and 3% water. The aqueous phase containing 61% water, 22%
MPD, 8% acetal and 4% acrolein. Eighty-three percent of the MPD was
converted to acetal. The yield based on acrolein reacted was
96%.
A similar reaction between MPD and acrolein was carried out at a
rate of 1.32 g./min. The maximum temperature observed in the resin
bed was 48.degree. C. The reaction product (30.7 g.) divided into
an acetal phase (26.3 g.) and an aqueous phase (4.4 g.). Conversion
of MPD to acetal was 82%. The compositions of the two layers were
similar to those above.
For the sake of comparison, a mixture of 0.5 mole 1,3-propanediol
and 0.55 mole acrolein were reacted at 50.degree. C in the presence
of 0.3 g. p-toluenesulfonic acid. Layers did not separate until the
reaction mixture was cooled to 26.degree. C. The mixture gave 18 g.
of an aqueous layer which contained about 40% diol, 21% acrolein,
10% 2-vinyl-1,3-dioxane and 25% water. The acetal layer of 49 g.
contained 63% 2-vinyl-1,3-dioxane, 23% acrolein, 8% diol and 5%
water, conversion to acetal was about 60% which represents only a
negligible increase over equilibrium conversion.
EXAMPLE 2
The addition of 0.05 ml. of 37% hydrochloric acid to a mixture of
18.02 g. (0.20 moles) of 2-methyl-1,3-propanediol and 12.12 g.
(0.216 moles) acrolein at 30.degree. C produced a rapid temperature
rise to 48.degree. C. The temperature was reduced to 30.degree. C
and maintained at that temperature for 2 hours with cooling. The
reaction mixture divided into 2 layers -- 25.62 g. of acetal layer
and 4.84 g. of aqueous layer. The conversion to acetal was 89%, of
which 98.8% was in the acetal layer. The acetal layer contained 88%
of VMD, 14% water, 6.8% acrolein and no diol. The water layer
contained 5% of VMD, 21% diol, 62.6% water and 3.8% acrolein.
EXAMPLE 3
The reaction of 26 g. (0.25 mole) of 2,2-dimethyl-1,3-propanediol
and 15.4 g. (0.275 mole) of acrolein was catalyzed with 0.1 ml. of
37% hydrochloric acid. At a controlled reaction temperature of
35.degree.-40.degree. C, separation into 2 layers began within 2
minutes. The conversion to acetal was 92%. A similar reaction at
27.degree. C produced 2 layers in 40 minutes and gave the same
conversion to acetal. The acetal layer contained 87.7% of
2-vinyl-5,5-dimethyl-1,3-dioxane (VDD), 1.0% diol, 1.0% water and
3.5% acrolein. The water layer contained 1.0% of VDD, 18% diol, 1%
acrolein and 77% water.
EXAMPLE 4
A mixture of 1 molar equivalent of 2,2-dimethyl-1,3-propanediol,
1.1 molar equivalents of acrolein and 1 molar equivalent of water
was passed through a column (3/4 inch .times. 4 inches) of 40 ml.
of strongly acidic cation exchange resin (Dowex MSC-1) at the rate
of 5 g./min. The maximum temperature in the resin bed was
55.degree. C when the bed was cooled by circulating water at
25.degree. C. A sample of 91.8 g. of reactor effluent separated
into 2 layers -- an acetal layer of 71.4 g. and an aqueous layer of
20.3 g. The acetal layer was composed of 88.8% acetal (VDD) and
small amounts of diol, 4% acrolein, 3% water and by-products. The
aqueous layer was 83.1% water, 13.7% diol, 2.2% acetal and 1.8%
acrolein. Conversion to acetal was 89%.
EXAMPLE 5
In this example, 2.0 molar equivalents of water were used with 1.0
molar equivalent of 2,2-dimethyl-1,3-propanediol, and 1.1
equivalents of acrolein. The resin bed was the same one used in the
previous example. At a flow rate of 2.7 g./min. and with cooling,
the maximum temperature in the resin bed was 30.degree. C. A sample
of 100.8 g. separated into 65.4 g. of acetal layer and 35.4 g. of
aqueous layer. The conversion to acetal was 82%. The acetal layer
contained 89.2% of VDD, 0.4% diol, 1.2% water and 5% acrolein. The
aqueous layer contained 3% of VDD, 14% diol, 80% water and 2%
acrolein.
Example 6
A mixture of 1.0 molar equivalent of 1,3-butanediol and 1.15 molar
equivalents of acrolein was passed through a bed of 10 ml. of the
ion exchange resin of Example 1 (50-100 mesh) at the rate of 0.65
g./min. The maximum temperature in the resin bed with cooling was
52.degree. C. A reactor effluent of 104.4 g. separated into 88.5 g.
acetal layer and 15.9 g. aqueous layer. The conversion to
2-vinyl-4-methyl-1,3-dioxane was 88%. The acetal layer contained
85.2% of 2-vinyl-4-methyl-1,3-dioxane, 2.7% diol, 3.3% water and
6.7% acrolein. The aqueous layer contained 8.6% of
2-vinyl-4-methyl-1,3-dioxane, 66.8% water, 20.9% diol and 6.2%
acrolein.
EXAMPLE 7
A mixture of 0.50 mole 2-methyl-2,4-pentanediol, 0.55 mole acrolein
and 0.2 g. polyphosphoric acid reacted at 50.degree. C to form 2
layers within 20 minutes. The conversion to acetal was 92%. The
acetal layer contained 90.5% of
2-vinyl-4,4,6-trimethyl-1,3-dioxane, 6% acrolein, 2% diol and 1.5%
water. The aqueous layer contained 3.6% acrolein, <1% of
2-vinyl-4,4,6-trimethyl-1,3-dioxane and 75% water.
EXAMPLE 8
A mixture of 0.2 mole 1,3-butanediol and 0.2 mole acetaldehyde was
stirred over 1.0 g. of the resin of Example 1 at
45.degree.-75.degree. C with no heating applied. The reaction
mixture separated into 21.0 g. of acetal layer and 3.5 g. of water
layer. Conversion to acetal (2,4-dimethyl-1,3-dioxane) was 90%. The
acetal layer contained 96% of 2,4-dimethyl-1,3-dioxane, 1.3% diol,
0.6% acetaldehyde and 2% H.sub.2 O. The aqueous layer contained
41.5% water, 0.8% acetaldehyde, 22% diol and 32%
2,4-dimethyl-1,3-dioxane.
EXAMPLE 9
A mixture of 0.4 mole n-amyl alcohol, 11.6 g. of propionaldehyde,
and 0.1 mole of 37% hydrochloric acid was reacted at
35.degree.-40.degree. C. Two layers formed within 5 minutes.
Separation of layers gave 45.2 g. of acetal layer (composition --
6% propionaldehyde, 23% amyl alcohol and 70% acetal). The
conversion to acetal was 72%.
EXAMPLE 10
A mixture of 0.6 mole n-butyl alcohol, 0.3 mole acetaldehyde and
0.1 ml. 37% hydrochloric acid was reacted at 45.degree.-50.degree.
C. Separation into two layers occurred in 1 minute. The aqueous
layer was 1.7 g. The conversion to acetal was 66-69%. The acetal
layer contained 67.5% of acetaldehyde, di-n-butanal acetal, 26%
n-butyl alcohol and 6% acetaldehyde.
EXAMPLE 11
This example shows the effect of excess diol.
A mixture of 4.50 g. (0.050 mole) of 2-methyl-1,3-propanediol and
1.73 g. (0.030 mole) of acrolein with 0.01 g. p-toluenesulfonic
acid was reacted at 40.degree.-50.degree. C. The reaction mixture
did not separate into layers. Analysis of the reaction mixture by
gas chromatography showed that 73% of the acrolein was converted to
acetal. When equimolar quantities of the reactants were used as in
Example 2, separation of layers occurred and the conversion to
acetal was 89%.
EXAMPLE 12
A mixture of 10.6 g. (.151 mole) of methacrolein and 14.4 g. (.138
mole) of 2,2-dimethyl-1,3-propanediol was stirred at
25.degree.-40.degree. C in the presence of 0.1% of hydrogen
chloride based on the total weight of the reactants. Two layers
separated in 10 minutes. The acetal layer (23.5 g.) contained 85.4%
of the 2-(2-propenyl)-5,5-dimethyl-1,3-dioxane, 9.4% methacrolein,
1.6% water and 1.4% of the diol. The aqueous layer (2.89 g.)
contained 75% water, 15% diol and 2% of methacrolein. Conversion of
diol to acetal was 93.5%.
EXAMPLE 13
A mixture of 21.2 g. of formaldehyde (0.20 mole) and 18.0 g. of
1,3-butanediol (0.20 mole) was reacted in the presence of 0.1%
hydrogen chloride based on the total weight of the reactants. The
mixture separated into 2 layers -- an aqueous layer of 5.1 g. and
an acetal layer of 33.3 g. The aqeuous layer contained 53% of water
and 44% of 1,3-butanediol. The acetal layer contained 1% water,
8.5% aldehyde and 90% 4-methyl-1,3-dioxane. The conversion to
acetal was 82%.
It is to be understood that any of the components and conditions
mentioned as suitable herein can be substituted for its counterpart
in the foregoing examples and that although the invention has been
described in considerable detail in the foregoing, such detail is
solely for the purpose of illustration. Variations can be made in
the invention by those skilled in the art without departing from
the spirit and scope of the invention except as set forth in the
claims.
* * * * *